In the case of contour Coke bottles from 1938 and earlier, some will have date marks, and some will not. Some date marks for bottles from the 1930s and late 1920s will appear as embossed two-digit numbers on the waist.

What do the numbers on the bottom of a bottle mean?

The number (within a triangle with rounded corners) found on the bottom of plastic bottles is a code indicating the type of plastic the bottle is made from, and pertains to the subject of recycling) .